Depression

I know a girl in my class (8th grade) and she was absent for about 2 weeks. When she got back a few of her closer friends told me she was depressed but I didn't really wanna get into it because I didn't wanna make her uncomfortable. But yesterday I noticed 2 band aids on her left wrist and today I saw self harm marks all over both of her wrists. I wanna talk to her and I want her to know that she can talk to me and I wouldn't judge her. we're not super close or anything but I still wanna do something. Any advice?